3,295 research outputs found

    Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian

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    We study the semi-classical motion of holes by exact numerical solution of the Luttinger model. The trajectories obtained for the heavy and light holes agree well with the higher order corrections to the abelian and the non-abelian adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378(2003)], respectively. It is found that the hole trajectories contain rapid oscillations reminiscent of the "Zitterbewegung" of relativistic electrons. We also comment on the non-conservation of helicity of the light holes.Comment: 4 pages, 5 fugure

    Thermodynamics of spin-1/2 tetrameric Heisenberg antiferromagnetic chain

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    The thermodynamic properties of a spin S=1/2 tetrameric Heisenberg antiferromagnetic chain with alternating interactions AF1-AF2-AF1-F (AF and F denote the antiferromagnetic and ferromagnetic couplings, respectively) are studied by means of the transfer-matrix renormalization group method and Jordan-Wigner transformation. It is found that in the absence of magnetic field, the thermodynamic behaviors are closely related to the gapped low-lying excitations, and a novel structure with three peaks in the temperature dependence of specific heat is unveiled. In a magnetic field, a phase diagram in the temperature-field plane for the couplings satisfying JAF1=JAF2=JF is obtained, in which various phases are identified. The temperature dependence of thermodynamic quantities including the magnetization, susceptibility and specific heat are studied to characterize the corresponding phases. It is disclosed that the magnetization has a crossover behavior at low temperature in the Luttinger liquid phase, which is shown falling into the same class as that in the S=1 Haldane chain. In the plateau regime, the thermodynamic behaviors alter at a certain field, which results from the crossing of two excitation spectra. By means of the fermion mapping, it is uncovered that the system has four spectra from fermion and hole excitations that are responsible for the observed thermodynamic behaviors.Comment: 10 pages, 10 figures, accepted by Phys. Rev.

    Antiferromagnetism and hole pair checkerboard in the vortex state of high Tc superconductors

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    We propose a microscopic state for the vortex phase of BSCO superconductors. Around the vortex core or above H_{c2}, the d wave hole pairs form a checkerboard localized in the commensurate antiferromagnetic background. We discuss this theory in connection with recent STM experiments.Comment: Final versio

    The cosmological origin of Higgs particles

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    A proposal of the cosmological origin of Higgs particles is given. We show, that the Higgs field could be created from the vacuum quantum conformal fluctuation of Anti-de Sitter space-time, the spontaneous breaking of vacuum symmetry, and the mass of Higgs particle are related to the cosmological constant of our universe,especially the theoretical estimated mass mH_{H} of Higgs particles is mH=−2μ2_{H}=\sqrt{-2\mu ^{2}} =∣Λ/π\sqrt{|\Lambda /\pi}.Comment: 7 pages,no figure

    A new approach to bulk viscosity in strange quark matter at high densities

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    A new method is proposed to compute the bulk viscosity in strange quark matter at high densities. Using the method it is straightforward to prove that the bulk viscosity is positive definite, which is not so easy to accomplish in other approaches especially for multi-component fluids like strange quark matter with light up and down quarks and massive strange quarks.Comment: 7pages, talk given in SQM2008. Minor revisions, including clarification and updated reference

    A practical synthesis of a novel DPAGT1 inhibitor, aminouridyl phenoxypiperidinbenzyl butanamide (APPB) for in vivo studies

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    Immunotherapy that targets N-linked glycans has not yet been developed due in large part to the lack of specificity of N-linked glycans between normal and malignant cells. N-Glycan chains are synthesized by the sequential action of glycosyl transferases in the Golgi apparatus. It is an overwhelming task to discover drug-like inhibitors of glycosyl transferases that block the synthesis of specific branching processes in cancer cells, killing tumor cells selectively. It has long been known that N-glycan biosynthesis can be inhibited by disruption of the first committed enzyme, dolichyl-phosphate N-acetylglucosaminephosphotransferase 1 (DPAGT1). Selective DPAGT1 inhibitors have the promising therapeutic potential for certain solid cancers that require increased branching of N-linked glycans in their growth progressions. Recently, we discovered that an anti-Clostridium difficile molecule, aminouridyl phenoxypiperidinbenzyl butanamide (APPB) showed DPAGT1 inhibitory activity with the IC_(50) value of 0.25 μM. It was confirmed that APPB inhibits N-glycosylation of β-catenin at 2.5 nM concentration. A sharp difference between APPB and tunicamycin was that the hemolytic activity of APPB is significantly attenuated (IC_(50) > 200 μM RBC). Water solubility of APPB is >350-times greater than that of tunicamycin (78.8 mg/mL for APPB, 60 min) for in vivo studies (PK/PD, safety profiles, and in vivo efficacy) using animal models. We have refined all steps in the previously reported synthesis for APPB for larger-scale. This article summarizes protocols of gram-scale synthesis of APPB and its physicochemical data, and a convenient DPAGT1 assay

    Topological insulators and superconductors

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    Topological insulators are new states of quantum matter which can not be adiabatically connected to conventional insulators and semiconductors. They are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time-reversal symmetry. These topological materials have been theoretically predicted and experimentally observed in a variety of systems, including HgTe quantum wells, BiSb alloys, and Bi2_2Te3_3 and Bi2_2Se3_3 crystals. We review theoretical models, materials properties and experimental results on two-dimensional and three-dimensional topological insulators, and discuss both the topological band theory and the topological field theory. Topological superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. We review the theory of topological superconductors in close analogy to the theory of topological insulators.Comment: 55 pages, 44 figures, Review article commissioned by the Review of Modern Physics. Please help us to improve the article by emailing us your comments and missing reference

    Universal Fluctuation of the Hall Conductance in the Random Magnetic Field

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    We show that the RMS fluctuation of the antisymmetric part of the Hall conductance of a planar mesoscopic metal in a random magnetic field with zero average is universal, of the order of e2/he^2/h, independent of the amplitude of the random magnetic field and the diffusion coefficient even in the weak field limit. This quantity is exactly zero in the case of ordinary scalar disorder. We propose an experiment to measure this surprising effect, and also discuss its implications on the localization physics of this system. Our result applies to some other systems with broken time-reversal ({\bf T}) symmetry.Comment: 4 pages, Revtex 3.0; added the paragraph regarding applicability to other systems with broken T-invariance, misc. minor change

    Critical phenomena in disc-percolation model and its application to relativistic heavy ion collisions

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    Through studying the critical phenomena in continuum-percolation of discs, we find a new approach to locate the critical point, i.e. using the inflection point of P∞P_\infty as an evaluation of the percolation threshold. The susceptibility, defined as the derivative of P∞P_\infty, possess finite-size scaling property, where the scaling exponent is the reciprocal of ν\nu -- the critical exponent of correlation length. The possible application of this approach to the study of the critical phenomena in relativistic heavy ion collisions is discussed. The critical point for deconfinement can be extracted by the inflection point of PQGPP_{\rm QGP} -- the probability for the event with QGP formation. The finite-size scaling of its derivative can give the critical exponent ν\nu, which is a rare case that can provide an experimental measure of a critical exponent in heavy ion collisions.Comment: 5 pages, 7 figure
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